1. Field of the Invention
The invention relates to a continuously variable transmission including two continuously variable transmission parts that are parallely disposed in a gear train.
2. Prior Art
Such a transmission is known from U.S. Pat. No. 1,709,346 for example, a central bevel gear being driven in these arrangements, said central bevel gear interacting through a respective friction ring with one or a plurality of oppositely directed output bevel gears oriented to be axially parallel with the input bevel gear and having their outer surface at a constant spacing from said input bevel gear. The friction rings are displaceable along a respective one of the gaps through a common frame so that a transmission ratio may be continuously varied between the input bevel gear and the output bevel gears. The respective ones of the driven members of the driven bevel gears are connected to the planet wheels of a planetary gear so that a torque applied by the input bevel gear is distributed to the respective ones of the driven bevel gears and added up again through the planetary gear, a constant rpm of the planet wheels and of the driven bevel gears being enforced by coupling the planet wheels. Although this arrangement solves the problem arising with such type bevel friction ring gears as well as with other continuously variable transmissions (CVT), which is that at high torques the continuous variability causes slippage that can only be prevented from occurring with high press-on forces and the resulting losses in efficiency. It however involves the major problem that the smallest manufacturing tolerances or inaccuracies will result in ulterior friction losses.